diff options
| author | Yuval Adam <yuv.adm@gmail.com> | 2012-10-29 23:06:01 +0200 |
|---|---|---|
| committer | Yuval Adam <yuv.adm@gmail.com> | 2012-10-29 23:06:01 +0200 |
| commit | 4ba8614c006f9828f0796c140bc3e13c9e67938c (patch) | |
| tree | ad204651c733250d27d20fce8820f9747c43c883 /utils/sine.c | |
| parent | e018ceebed74b8223482bc9d1ed0b31c938381da (diff) | |
Added utils
Diffstat (limited to 'utils/sine.c')
| -rw-r--r-- | utils/sine.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/utils/sine.c b/utils/sine.c new file mode 100644 index 0000000..7b971ca --- /dev/null +++ b/utils/sine.c @@ -0,0 +1,125 @@ +//*****************************************************************************
+//
+// sine.c - Fixed point sine trigonometric function.
+//
+// Copyright (c) 2006-2012 Texas Instruments Incorporated. All rights reserved.
+// Software License Agreement
+//
+// Texas Instruments (TI) is supplying this software for use solely and
+// exclusively on TI's microcontroller products. The software is owned by
+// TI and/or its suppliers, and is protected under applicable copyright
+// laws. You may not combine this software with "viral" open-source
+// software in order to form a larger program.
+//
+// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS.
+// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT
+// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY
+// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
+// DAMAGES, FOR ANY REASON WHATSOEVER.
+//
+// This is part of revision 9453 of the Stellaris Firmware Development Package.
+//
+//*****************************************************************************
+
+#include "utils/sine.h"
+
+//*****************************************************************************
+//
+//! \addtogroup sine_api
+//! @{
+//
+//*****************************************************************************
+
+//*****************************************************************************
+//
+// A table of the value of the sine function for the first ninety degrees with
+// 129 entries (that is, [0] = 0 degrees, [128] = 90 degrees). Each entry is
+// in 0.16 fixed point notation.
+//
+//*****************************************************************************
+static const unsigned short g_pusFixedSineTable[] =
+{
+ 0x0000, 0x0324, 0x0648, 0x096C, 0x0C8F, 0x0FB2, 0x12D5, 0x15F6, 0x1917,
+ 0x1C37, 0x1F56, 0x2273, 0x2590, 0x28AA, 0x2BC4, 0x2EDB, 0x31F1, 0x3505,
+ 0x3817, 0x3B26, 0x3E33, 0x413E, 0x4447, 0x474D, 0x4A50, 0x4D50, 0x504D,
+ 0x5347, 0x563E, 0x5931, 0x5C22, 0x5F0E, 0x61F7, 0x64DC, 0x67BD, 0x6A9B,
+ 0x6D74, 0x7049, 0x7319, 0x75E5, 0x78AD, 0x7B70, 0x7E2E, 0x80E7, 0x839C,
+ 0x864B, 0x88F5, 0x8B9A, 0x8E39, 0x90D3, 0x9368, 0x95F6, 0x987F, 0x9B02,
+ 0x9D7F, 0x9FF6, 0xA267, 0xA4D2, 0xA736, 0xA994, 0xABEB, 0xAE3B, 0xB085,
+ 0xB2C8, 0xB504, 0xB73A, 0xB968, 0xBB8F, 0xBDAE, 0xBFC7, 0xC1D8, 0xC3E2,
+ 0xC5E4, 0xC7DE, 0xC9D1, 0xCBBB, 0xCD9F, 0xCF7A, 0xD14D, 0xD318, 0xD4DB,
+ 0xD695, 0xD848, 0xD9F2, 0xDB94, 0xDD2D, 0xDEBE, 0xE046, 0xE1C5, 0xE33C,
+ 0xE4AA, 0xE60F, 0xE76B, 0xE8BF, 0xEA09, 0xEB4B, 0xEC83, 0xEDB2, 0xEED8,
+ 0xEFF5, 0xF109, 0xF213, 0xF314, 0xF40B, 0xF4FA, 0xF5DE, 0xF6BA, 0xF78B,
+ 0xF853, 0xF912, 0xF9C7, 0xFA73, 0xFB14, 0xFBAC, 0xFC3B, 0xFCBF, 0xFD3A,
+ 0xFDAB, 0xFE13, 0xFE70, 0xFEC4, 0xFF0E, 0xFF4E, 0xFF84, 0xFFB1, 0xFFD3,
+ 0xFFEC, 0xFFFB, 0xFFFF
+};
+
+//*****************************************************************************
+//
+//! Computes an approximation of the sine of the input angle.
+//!
+//! \param ulAngle is an angle expressed as a 0.32 fixed-point value that is
+//! the percentage of the way around a circle.
+//!
+//! This function computes the sine for the given input angle. The angle is
+//! specified in 0.32 fixed point format, and is therefore always between 0 and
+//! 360 degrees, inclusive of 0 and exclusive of 360.
+//!
+//! \return Returns the sine of the angle, in 16.16 fixed point format.
+//
+//*****************************************************************************
+long
+sine(unsigned long ulAngle)
+{
+ unsigned long ulIdx;
+
+ //
+ // Add 0.5 to the angle. Since only the upper 9 bits are used to compute
+ // the sine value, adding one to the tenth bit is 0.5 from the point of
+ // view of the sine table.
+ //
+ ulAngle += 0x00400000;
+
+ //
+ // Get the index into the sine table from bits 30:23.
+ //
+ ulIdx = (ulAngle >> 23) & 255;
+
+ //
+ // If bit 30 is set, the angle is between 90 and 180 or 270 and 360. In
+ // these cases, the sine value is decreasing from one instead of increasing
+ // from zero. The indexing into the table needs to be reversed.
+ //
+ if(ulAngle & 0x40000000)
+ {
+ ulIdx = 256 - ulIdx;
+ }
+
+ //
+ // Get the value of the sine.
+ //
+ ulIdx = g_pusFixedSineTable[ulIdx];
+
+ //
+ // If bit 31 is set, the angle is between 180 and 360. In this case, the
+ // sine value is negative; otherwise it is positive.
+ //
+ if(ulAngle & 0x80000000)
+ {
+ return(0 - ulIdx);
+ }
+ else
+ {
+ return(ulIdx);
+ }
+}
+
+//*****************************************************************************
+//
+// Close the Doxygen group.
+//! @}
+//
+//*****************************************************************************
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